A user of a motor vehicle having an internal combustion engine may be provided with information regarding the oil pressure in the engine. Specifically, the user may be provided with an indication if the oil pressure is so low that damage to the engine may occur. With some engines this is achieved by using a pressure actuated switch and a tell-tale red light incorporated as part of an instrument cluster of the motor vehicle. If the oil pressure is below a particular level then the switch closes and the red light is illuminated to warn the driver that the oil pressure is dangerously low.
It is increasingly becoming a legal requirement for the oil pressure of the engine to be monitored for fuel economy related features such as, for example, a two stage oil pump and this may require the use of an oil pressure sensor that can provide a signal indicative of the oil pressure in the engine. However, a dedicated oil pressure sensor may increase the cost and complexity of the engine.
As such in one approach, a system for monitoring the oil pressure in a cost effective and simplified manner is provided. An oil pressure monitoring system for an internal combustion engine having a variable camshaft timing system including at least one engine oil pressure operated camshaft timing actuator wherein the system comprises a camshaft timing sensor providing an output signal indicative of the operation of each respective camshaft timing actuator, an electronic processing unit receiving the signal from each respective variable camshaft timing sensor and use the received signal to provide an output indicative of the oil pressure of the engine, is provided.
In some examples, the output signal received from each variable camshaft timing sensor may be information regarding the phasing of the respective camshaft and the electronic processing unit is operable to determine a phase angle rate of change of the respective variable camshaft timing actuator from each received signal and use the determined rate of phase angle change to estimate the current oil pressure of the engine.
Further in some embodiments, the oil pressure monitoring system may include two camshaft timing actuators each having a respective camshaft timing sensor associated therewith to provide a phase angle signal to the electronic processing unit and the electronic processing unit may be operable to estimate the current oil pressure based upon a phase angle rate of change of the camshaft timing actuators derived from the received phase angle signals.
Additionally in some examples, the oil pressure may be estimated using one of a look-up table and an algorithm stored in the electronic processing unit.
In another example, the oil pressure monitoring system may include at least two camshaft timing actuators each having an engine oil pressure released lock to hold the respective actuator in a predetermined position and a respective camshaft timing sensor associated with each actuator to provide a phase angle signal to the electronic processing unit and, if the signals from the camshaft timing sensors indicate that at least two of the actuators are not operating, the electronic processing unit may be operable to provide an output indicative that the oil pressure of the engine is below a low oil pressure threshold value.
Additionally in some examples, the oil pressure monitoring system may further comprise a Human Machine Interface and the electronic processing unit may provide the output via the Human Machine Interface.
The oil pressure monitoring system may further comprise an ignition switch and a sensor providing a signal indicative of whether the engine is running to the electronic processing unit and the electronic processing unit may be further operable to determine whether the engine is running and, if the engine is not running and the ignition switch is on, to provide the output indicative that the oil pressure of the engine is below the low oil pressure threshold value.
Further in some examples, the electronic processing unit may be further operable to maintain an oil pressure status log of the oil pressure status when the oil pressure was last checked and, if no camshaft phase changes are being requested and at least one of the camshaft timing actuators is sensed to be operating, the electronic processing unit is operable to use the last oil pressure status recorded in the log to determine whether the oil pressure is below the low oil pressure threshold value.
In another example, an internal combustion engine having the variable camshaft timing system and the oil pressure monitoring system described above may be provided.
Further in some examples, a method for monitoring the oil pressure of an internal combustion engine is provided. The engine includes a variable camshaft timing system including an engine oil pressure operated camshaft timing actuator and a camshaft timing sensor. Furthermore, the method comprises providing, via the sensor, a signal indicative of operation of the camshaft timing actuator; and providing an output indicative of the engine oil pressure of the engine based on the signal.
In some examples, at least two camshaft timing actuators each having an engine oil pressure released lock to hold the respective actuator in a predetermined position and a respective camshaft timing sensor associated with each actuator to provide a phase angle signal and the method may further comprise providing an indication that the oil pressure of the engine is below a low oil pressure threshold value if the signals from the camshaft timing sensors indicate that at least two of the actuators are not operating.
The method may further comprise determining whether an ignition switch is on and the engine is running and, if the ignition switch is on and the engine is not running, providing an output indicative that the oil pressure of the engine is below the low oil pressure threshold value.
The method may further comprise maintaining an oil pressure status log of the oil pressure the oil pressure when the oil pressure was last checked and, if no camshaft phase changes are being requested and a least one camshaft actuator is sensed to be operating using the last oil pressure status recorded in the log.
In some examples the method may further comprise determining a phase angle rate of change of each camshaft timing actuators and using the determined rate of change to estimate the current oil pressure of the engine.
The method may further comprise using one of a look-up table and an algorithm to estimate the current oil pressure.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.
The Invention is described in more detail below with reference to FIGS. 1-4.